Modulation

Modulating your voice means moving the pitch up and down. The alternative is
to keep an even pitch throughout the sentence, which at best will sound odd and
at worst dull, boring or confusing.

Pitch change

A change in frequency in speaking tone provides the listener with a signal
that something is happening. Modulation can thus be used to enhance emphasis in
words, with rising and lowering tones adding subtle meaning.

Going down for authority

A downwards pitch adds authority to a sentence. It gives imperative
that seeks unquestioning acceptance. To go down, you need to be up, so gradually
increase the pitch of your voice beforehand to give yourself the ability to
suddenly drop the pitch on an important point. The pitch of the sentence may
thus go up and down several times as key words are emphasized.

You know, it has now become important that you
work harder so you can support your family.

Looking back at this sentence, the emphasized, low-pitched words stand out
and combine together to form the key message that you want to get across.

Going up for engagement

An upwards pitch adds interest to a sentence. It questions and provokes
engagement and response. Going up starts from a medium or low pitch. You thus
cannot stay at this involving level for long. Sometimes when people want to
invite the other person they will use a fragmented sentence that contains
several rising-pitch words to repeated the invitation.

I was just wondering...whether you would like...maybe
to come today?

Repetition

A regular up and down modulation creates a pattern of repetition that is not
initially recognized and can thus be used to 'creep up on' the other person.

Pounding home a point

When someone is making a point about something, their pitch will go up and
down as they repeatedly pound the point of authority. This may well be done in a
rhythmic way, accompanied with pounding of a finger or fist to exaggerate
further. The repetition may also emphasized further by repeating a single word
or phrase.

I was never there, I would never do a thing
like that and I have never been so insulted in my entire life.

Hypnotic suggestion

Repetition and modulation is a common element of hypnotic speech. The modulation pulls
people in with the impression of something worth listening to, then the
repetition sends them into a trance. This can be a deliberate method for public
speakers that can be used to lull a whole audience into a suggestible state
before the real message is slipped past the weakened cognitive defenses.

Making it interesting

Listen to a beginner actor or salesperson: as they concentrate on the words, the modulation
goes out of the window and they sound odd and wooden. Modulation makes meaning.

Listen to the TV presenter introducing a program or reading the news. Notice
how their voice goes up and down very deliberately. They know very well what
they are doing.

Notice also how the TV presenter moves their head and their in time with
the modulation. Their body is often obscured by a table or even off-camera.
They must thus use just their voice and their head to convey meaning.